ci: add Node.js 16 in the test matrix

Author: darrachequesne

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [10.x, 12.x, 14.x]
+        node-version: [12, 14, 16]
 
     steps:
       - uses: actions/checkout@v2